Apparatus for sorting products

ABSTRACT

A machine for sorting products employing light sensitive cells for receiving light reflected from a product passing through a viewing zone to detect products that are too light, too dark or defective. The signals from the light sensitive cells are amplified and passed through active filters which eliminate high frequency signals, transients, etc., therefrom. Output from the active filters is supplied to comparators and also to a peak detector as well as to a product flow indicator which controls a signal, such as a light, to indicate if the flow of products through the viewing zone is interrupted for any reason. A resistor to ground supplies bias to a transistor which supplies a positive biasing voltage to the two comparators to keep these comparators turned off except when a positive peak pulse is supplied to the transistor from the peak detector. This gates the comparators on and if the signal from the product corresponds to a product that is either too light or too dark one of the other of the comparators transmits a positive pulse to a pulse stretching circuit which supplies a short pulse to a delay circuit comprising a 64 bit shift register which functions as a memory and predetermined delay and is controlled by pulses supplied by a clock pulse generator. A selected output of the shift register supplies a delay pulse to a transistor which is connected to the pulse stretcher and supplies a pulse of predetermined duration to the input of a transistor amplifier. This transistor amplifier controls the energization of the solenoid of the valve controlling the product rejector which is used to deflect the product to be rejected from the main product stream.

United States Patent 1 Wood 9 1 Dec. 4, 1973 APPARATUS FOR SORTINGPRODUCTS [76] Inventor: Richard A. Wood, 150 Cumulus,

Sunnyvale, Calif. 95030 [22] Filed: Apr. 26, 1972 [21] Appl. No.:247,844

Primary Examiner-Richard A. Schacher Assistant ExaminerGene A. ChurchAttorney-Ben J. Chromy et a1.

[57] ABSTRACT A machine for sorting products employing light sensitivecells for receiving light reflected from a product passing through aviewing zone to detect products that are too light, too dark ordefective. The signals from the light sensitive cells are amplified andpassed through active filters which eliminate high frequency signals,transients, etc., therefrom. Output from the active filters is suppliedto comparators and also to a peak detector as well as to a product flowindicator which controls a signal, such as a light, to indicate if theflow of products through the viewing zone is interrupted for any reason.A resistor to ground supplies bias to a transistor which supplies apositive biasing voltage to the two comparators to keep thesecomparators turned off except when a positive peak pulse is supplied tothe transistor from the peak detector. This gates the comparators on andif the signal from the product corresponds to a product that is eithertoo light or too dark one of the other of the comparators transmits apositive pulse to a pulse stretching circuit which supplies a shortpulse to a delay circuit comprising a 64 bit shift register whichfunctions as a memory and predetermined delay and is controlled bypulses supplied by a clock pulse generator. A selected output of theshift register supplies a delay pulse to a transistor which is connectedto the pulse stretcher and supplies a pulse of predetermined duration tothe input of a transistor amplifier. This transistor amplifier controlsthe energization of the solenoid of the valve controlling the productrejector which is used to defleet the product to be rejected from themain product stream.

7 Claims, 2 Drawing Figures PATENIEH DEC 4 I975 SHEET 2 [IF 2 h N w m wm m optical APPARATUS FoR- soRT nG PRODUCTS DESCRIPTION OFTHE INVENTIONThis invention relates to an electrical apparatus for sorting products.I t I An object of this invention is to provide an improved productsorting apparatus which is efficient andhighly reliable in operation.

Another object of this invention is to provide an improved high speedsorting apparatus for sorting products such as beans, which are toolight or too dark or which have blemishes thereon, from a rapidlyflowing single file stream of the product.

Another object of this invention is to provide an improved productsorting apparatus in which the products are passed through a viewingzone in which electrical signals corresponding to the products aregeneratedand the signals corresponding to the productsthat are V inputof a shift register which has a 6.4 bit'memory. The

too light or too dark or have other defects are selected a and used toactivate a rejecting device for deflecting these products from the mainproduct stream.

Another object of this invention is to provide an apparatus for sortingproducts that is easy to operate'by relatively unskilled labor.

Another object of this invention is to provide an improved apparatus ofmodular construction for sorting products, said apparatus having lowelectric power consumption. I

Other and further objects of this invention will be apparent to thoseskilled inthe art to which it relates from the following specification,claims anddrawing.

In accordance with this invention there is provided an apparatus forhigh speed sorting of small objects such as beans which are fed bygravity through the viewing head of the apparatus. The objects areilluminated in the viewing head and signals depending upon opticalcharacteristics of the objects are developed in this head by photocellsprovided thereto which are con nected in series to the input of a seriesof operationalamplifiers. The output of the operational amplifiers isprovided to a peak detector which develops a sharp voltage pulse foreach product passing through the viewing head. The sharp voltage pulsescorresponding to the products are supplied to the base of a gatingtransistor which supplies strobingpulses to the compensating terminalsof a pair of operational amplifiers which are used as comparators. Theinputs of the comparators are biased, for example, sothat one of thecomparators is responsive to signals derivedfrom products that are toolight and the other of the comparators responds to signals derived fromproducts that are too dark. The outputs of the comparators are suppliedover a common output line to one input of a'pulse stretcher which is ofthe type requiring negligible recovery time. Thus when a tooslightproduct is passing through the viewing head the comparator biased'torespond to such a product signal is gated and supplies an output pulseto one one millisecond pulse and this-pulse is supplied to the shiftregister has a much wider range of timing adjustment than may beobtained in one shot type timed delays. Thus, the shift register'incombination with thc clock pulse generator provide the correctdclay foren- -ergization of the solenoid that controls the-air jet for deflectingthe rejected product. This time delay must correspond to the timeinterval required for the rejected product to travel from the opticalhead to the dc-- fleeting airjet. The output from the shift register isprovided to the second section of the pulse stretcher which supplies a 4millisecond pulse to the transistor amplifier that controls theenergization of the solenoid valve controlling the air jet. A highvoltage transistor is used to drive the solenoid of the valve since thistype of transistor does not require kick'back protection and the netresult is faster solenoid operation. A

Further details. and features of this invention will be set forth in thefollowing specification, claims and drawingin which, briefly;' I I FIG.1 illustrates one portion ofthe schematic wiring diagram ofthisinvention; and

FIG. 2-illustrates the otherportion of the schematic -wiring diagram ofthis invention, and these figures are this series combination isconnected between the posito be used together with the lines 50 and 56of both figures being joined. a

Referring tothe drawing in detail, reference numeral 10 designates atube which may be of plastic, glass, or the like. This tube forms achannel through which products 11 such as beans and the like which areto be inspected drop in a single file. Thus the products 11 drop throughan optical viewing head positioned around the tube 10. This opticalviewing head includes two circular light sensitive cells 12 whichencirclethe tube 10 and which receivelight reflected from the product 11as it is illuminated by the light sources 13. These light sources arearranged so that they do not illuminate the light sensitive cells 12directly and these cells receive their illumination only by lightreflected from the single file product, such as beans which may beeither wet or dry. g

This apparatusis provided with an amplifier arrangement'employingoperational amplifiers 14, 15, 16, 17 and 18 which may be of the type741C manufactured by Fairchild Semi-conductor. Amplifiers 14 to 17,inelusive, are provided with feedback resistors 19, 20, 21,

and 22, respectively, which are connected between the 4 negative inputsand outputs of these amplifiers. In addi-.

tion amplifiers l6 and 17 are provided with capacitors 23 and 24 whichare connected across resistors 21 and 22, respectively, to providefilters by means of which the high frequency spikes and transients arefiltered out of circuits of the amplifiers.

Light sensitive cells 12 are connected in series and tive and negativeinputs of amplifier 14. hi addition a biasing potential is provided tothe negative input of amplifier 14 through the potentiometer 25 andresistor 26 which is connected between the amplifier input and thevariable contact of the potentiometer. The terminals of thepotentiometer are connected to the positive and negative terminals of a12 voltD.C. supply. The bottom terminals of resistors 27 to 34,inclusive, are connected to the ground line 35 which is also connectedto the positive terminal of the amplifier 14. The

upper terminal of the gain control potentiometer 27 is connected to theoutput of amplifier 14 and the vari- 3 able contact thereof is connectedto the positive input terminal of amplifier 15. The upper terminal ofresistor 28 is connected to the negative input terminal of amplifier land the upper terminal of resistor 29 is connected to the output ofamplifier 15. The upper'terminal of resistor 30 is connected to thepositive input terminal of amplifier 16 and the upper terminal ofresistor 31 is connected to the output of this amplifier. The upperterminal of resistor 32 is connected to the positive input terminal ofamplifier 17. The negative input terminals of amplifiers 16 and 17 areconnected to the outputs of amplifiers l5 and 16, respectively, throughresistors 36 and 37, respectively.

The output of amplifier 17 is connected to the anode of diode 38 and thecathode of this diode is connected the base of transistor 57. Thecollector of transistor 57- to the upper terminal of resistor 33 andalso to the left hand side of capacitor 39. The right hand side ofcapacitor 39 is connected to the negative input terminal of amplifier 18and to the anode of diode 40a and cathode of diode 40d of the feedbackcircuit 40. The upper terminal of resistor 34 is connected to thepositive input terminal of amplifier 18 and the output of thisamplifieris connected to the cathode of diode 40b and anode of diode 40cof feedback circuit 40. The diodes 40a, 40b, 40c and 40d of feedbackcircuit 40are connected into a ring and the positive 17 volt source isconnected to cathode of diode 40a and anode of diode 40b throughresistor 40e and diode 40f. Likewise, the cathode of diode 40c and anodeof diode 40d are connected to the negative 12 volt source throughresistor 40g.

Amplifiers 14 and 16 are connected as signal inverters so that theoutput of amplifier 17 to the capacitor 39 through diode 38 is positive.This positive signal is also supplied to the positive input terminal ofopera tional amplifier 41 through the resistor 42. The output ofamplifier 41 is connected to the base of transistor 43 through theresistor 44 so that this amplifier supplies the bias to the base of thistransistor as long as the product ll flows through the tube 10. Thus aslong as output signal is applied from amplifier 17 to maintain thecapacitor 45 charged the amplifier 41 supplies a bias potential to thebase of transistor 43 to maintain this transistor in non-conductingcondition, and as long as this condition is maintained relay winding 46is not energized. When the product flow through the tube 10 isinterrupted the signal to amplifier 41 is interrupted and the charge oncapacitor 45 is dissipated. The bias to the base of transistor 43 isinterrupted and this transistor becomes conductive so that the windingof relay 46 which is energized from the positive 17 volt line 47. Relay46 then opens contacts 48 associated therewith and the current supply tothe indicator lamp 49 from the plus 17 volt line 47 is interrupted. Theoperator of this apparatus is then informed that the feeding of productthrough tube 10 has been interrupted.

Line 50 is provided between the left hand side of capacitor 39 and thepositive input terminal of comparator 51 and the negative input terminalof comparator 52 through resistor 53. Comparators 51 and 52 may beoperational amplifiers of the type 748C manufactured by FairchildSemiconductors. While these devices are basically operational amplifiersthey are supplied with strobing pulses on their compensating terminalsso that they function as comparators. Capacitors 54 and 55 are connectedto the compensating tenninals of comparators 51 and 52, respectively, toprevent oscillation thereof on high frequencies. Line 56 is connected tothe output of amplifier 18 to provide bias potential to is connected byline 58 to the compensating inputs of comparators 51 and 52 throughresistors 59 and 60, respectively, so that these comparators are turnedoff as long as positive voltage is supplied thereto from transistor 57over line 58.

Positive bias is supplied to the negative input termi nal of comparator51 and the positive input terminal of comparator 52 from the positive 17volt line 61 I 50 which are above a predetermined value and variableresistor 63 is adjusted to bias comparator 52 so that this comparatorresponds to voltage pulses coming over line 50 which-are below apredetermined value. Comparators 51 and 52 will, of course, not beresponsive to these voltage pulses unless at the same time a peakvoltage pulse is received by the base of transistor 57 over line 56 sothat the compensating bias supplied by transistor 57 over line 58 isremoved or reduced from the compensating circuits of comparators 51 and52 thereby permitting these comparators to respond to the voltage pulsessupplied thereto over line 50 assuming those voltage pulses are in theranges mentioned above.

The outputs of comparators 51 and 52 are connected to output lines 66and 67, respectively, and these lines are connected to diode rectifiers68 and 69, respectively. The cathodes of diodes 68 and 69 are connectedtogether to line 70 which is connected to one of the inputs of the pulsestretcher 71. Pulse stretcher 71 may be of the Model MC675 Tmanufactured by Motorola, and this device has the advantage in that itrequires no recovery time. When a pulse is transmitted over line 70 tothis pulse stretcher it supplies a one millisecond pulse from its outputnumber 6 to line 72 which is connected to the base of transistor 73.Transistor 73 functions as a pulse inverter and supplies a negativepulse from its collector to line 75 which is connected to input number 6of the shift register 76. The collector of transistor 73 is alsoconnected through resistor 74 to the positive 17 volt line 61.

Shift register 76 comprises 3 units which are designated as 77, 78 and79 and which are capable of storing 64 bits. These units are connectedby line 80 to the output of the clock pulse generator 81. Generator 8]may be of the Model MC 667 T clock generator manufactured by Motorola.The clock rate of generator 81 iseontrolled by the variable resistor 82which is connected to terminals numbered 1 1 and 14 of the generator. Achoke coil 83 is connected between the positive 17 volt line 61 and theterminal number 14 of the gen- .erator for supplying'D.C. currentthereto and suppressing transients. A clock indicator 84 which comprisesa light-emitting diode is connected to terminal number 6 of thegenerator through the Darlington amplifier 85 and resistor 86. The lightemitting diode indicates when the clock generator is functioningproperly. The cathode of light emitting diode 84 is connected to the 30volt line 88 through resistor 89.

A current limiting resistor 90 is connected between the line 88 and theanode of diode 91, the cathode of which is connected to the 17 volt line61. The output of the shift register 76 is provided from terminal numherthereof to line 9 2 which is connected to the input of theDarlington'amplifier 93 through resistor 94. The

-output of the Darlington amplifier 93 is supplied to the a producthaving unacceptableoptical properties, I

tion of pulse stretcher 71. The Darlington amplifiers 85 and 93 providea convenient means for furnishing the current required by the emittingdiodes 84 and 95. The output of the second section of pulse stretcher 71is supplied to line 98 from terminal number 8. Thus when a pulse issupplied to this section of the pulse'stretcher a 4.8 millisecond pulseis transmittedover line 98 therefrom to the base of transistor 99through resistor 100. The collector of transistor 99 is connected to thebase of transistor 101 through resistor 102 and the COllector oftransistor 101 is connected to the base of the power transistor 103which controls the supplying of current to the solenoid 104. Thus when a4.8 millisecond pulse is supplied by the pulse stretcher 71 over line 98to transistor 99, solenoid '104 is energized through I the other of saidcomparators to respond to signals derived from products having otherpredetermined optitransistor 103 and the valve 105 is opened. Valve 105controls the air jet which is used to deflect the product to be rejectedfrom the column 10. a

While I have shown and described certain preferred embodiments of theinvention, it is apparent that the invention is capable of variation andmodification from the form shown so that the scope thereof should belimited only by the proper scope of the claims appended hereto.

What I claim is: Y

1. In apparatus for sorting products comprising the combination of lightsensitive means, rneans passing a single file of products to be sortedpast said first mentioned means, means illuminating the products insaidsingle file as they pass said light sensitive means to developsignals corresponding to the individual products means amplifying saidsignals, a peak voltage detector connected to said amplifying means,said detector developing relatively short pulses corresponding to thepeaks of the signals from said products, comparator means responsive tosignals from products having unacceptable optical properties, gatingmeans connected to said comparator means and to said peak detectorrendering said comparator means non-responsive tosaid signals exceptwhen a pulse is received by saidgating means from the output of saidpeak detector, signal stretching means connected to the output of saidcom parator means for receiving a signal corresponding to meansconnecting'said signal stretching means to a delay means providing apredetermined delay to the signal supplied thereto from said signalstretching means, means connected to the output of said delay means forcontrolling the energization of a solenoid valve after saidpredetermined delay, said solenoid valve controlling an airjet todeflect the product having unacceptable optical properties from saidsingle file after said product has left the scanning zone occupied bysaid light sensitive means. I

2. In apparatus for sorting products comprising the combination as setforth in claim I, further characterized in that said comparator meanscomprises at least two comparators, means biasing one of saidcomparators to respond to signals derived from products havingpredetermined optical propertiesand means biasing cal properties. V

3. In apparatus for sorting products comprising the combination as setforth in claim- 2, further characterized in that said comparatorscomprise'operational am plifiers and connections between compensatingterminals of said operational amplifiers and said transistor gating saidoperational amplifiers to transmit an output pulse if a signalcorresponding to a' product of unacceptable optical properties issimultaneously supplied to the input of either of said operationalamplifiers.

4. In apparatus for sorting products comprising the combination as setforth in'claim 1, further characterized in that said gating meanscomprises a transistor section connected to said delay means forproducing a substantially stretched pulse to control the energization ofsaid solenoid.

7. In apparatus for sorting products comprising the combination-as setforth in claim 1, further comprising an alarm connected to saidamplifying means to indicate interruption of the single file ofproducts.

1. In apparatus for sorting products comprising the combination of lightsensitive means, means passing a single file of products to be sortedpast said first mentioned means, means illuminating the products in saidsingle file as they pass said light sensitive means to develop signalscorresponding to the individual products, means amplifying said signals,a peak voltage detector connected to said amplifying means, saiddetector developing relatively short pulses corresponding to the peaksof the signals from said products, comparator means responsive tosignals from products having unacceptable optical properties, gatingmeans connected to said comparator means and to said peak detectorrendering said comparator means nonresponsive to said signals exceptwhen a pulse is received by said gating means from the output of saidpeak detector, signal stretching means connected to the output of saidcomparator means for receiving a signal corresponding to a producthaving unacceptable optical properties, means connecting said signalstretching means to a delay means providing a predetermined delay to thesignal supplied thereto from said signal stretching means, meansconnected to the output of said delay means for controlling theenergization of a solenoid valve after said predetermined delay, saidsolenoid valve controlling an air jet to deflect the product havingunacceptable optical properties from said single file after said producthas left the scanning zone occupied by said light sensitive means.
 2. Inapparatus for sorting products comprising the combination as set forthin claim 1, further characterized in that said comparator meanscomprises at least two comparators, means biasing one of saidcomparators to respond to signals derived from products havingpredetermined optical properties and means biasing the other of saidcomparators to respond to signals derived from producTs having otherpredetermined optical properties.
 3. In apparatus for sorting productscomprising the combination as set forth in claim 2, furthercharacterized in that said comparators comprise operational amplifiersand connections between compensating terminals of said operationalamplifiers and said transistor gating said operational amplifiers totransmit an output pulse if a signal corresponding to a product ofunacceptable optical properties is simultaneously supplied to the inputof either of said operational amplifiers.
 4. In apparatus for sortingproducts comprising the combination as set forth in claim 1, furthercharacterized in that said gating means comprises a transistor and saidpulse from said peak detector is transmitted to the base of saidtransistor.
 5. In apparatus for sorting products comprising thecombination as set forth in claim 1, further characterized in that saiddelay means comprises a shift register and a clock pulse generatorconnected to said shift register.
 6. In apparatus for sorting productscomprising the combination as set forth in claim 1, furthercharacterized in that said signal stretching means comprises a sectionconnected to said delay means for producing a substantially stretchedpulse to control the energization of said solenoid.
 7. In apparatus forsorting products comprising the combination as set forth in claim 1,further comprising an alarm connected to said amplifying means toindicate interruption of the single file of products.